Goldstone Apple Valley Radio Telescope (GAVRT) Black Hole Patrol: Monitoring Quasar Radio Flux Densities from 2015 to 2022

Supermassive black holes can launch highly relativistic jets that emit at radio frequencies due to synchrotron emission. Tracking the radio flux densities of quasars can probe many aspects of jets that are linked to their launching, structures, and geometries. The Goldstone-Apple Valley Radio Telescope (GAVRT) project is a 20 year partnership between the Lewis Center for Educational Research (LCER) and Jet Propulsion Laboratory, California Institute of Technology (JPL) to provide scientific research opportunities for students in grades kindergarten to 12 (K-12). Two (DSS 13 & 28) Deep Space Network (DSN) antennas, each of 34 m in diameter, are maintained by the DSN and JPL and operated by students under the guidance of the LCER. As part of the GAVRT partnership, the Black Hole Patrol science campaign was initiated in 2013. A sample of 26 quasars was selected for monitoring radio flux density at 8.45 GHz (3.5 cm wavelength). Quasars were observed with a typical cadence of weekly to months using antennas DSS13 and/or DSS28 when available. An epoch source flux measurement was estimated averaging the calibrated scan flux density data for the those observed on a single day. This iposter describes the observation program and presents the time series of the radio flux densities (light curves), from which we extract measures of flux density variability. We find that nearly half of the quasars in the GAVRT Black Hole Patrol sample show measurable source variability. We also discuss particularly significant variability or notable sources.

We acknowledge the participation of students and teachers in the GAVRT quasar monitoring observations made during 2015 to 2022 from a number of schools, 5 in Australia, 1 in Chile, 2 in Guam, and 96 in USA. This work was performed at the Lewis Center for Educational Research with support from the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.